Updated three Joomla websites (so far) from J! 3.9.6 to J! 3.9.8 without any problems. Front- and back-end access all seem to work OK. Thanks, everyone.

UPDATE: Updated another half-dozen websites from J! 3.9.6 to J! 3.9.8 without any problems. Tip: Make sure that you "check for updates" in case the Joomla! Update component shows the latest update is J! 3.9.7.